Tropical hibiscus are highly sensitive to phosphorus (the middle “P” number on fertilizers) and an excessive amount will kill the plant. Do not use so-called “bloom fertilizers” on them. Instead tropical hibiscus need a lot of potash to bloom properly (the last number or “K” on fertilizers). Palm fertilizers are widely available and usually have the proper ratio of a medium-low-high NPK ratio along with needed minors.
The pesticide malathion will defoliate tropical hibiscus. Do not use it for pest control.
As Tahitian taui is tender, ensure temperatures are mild enough to plant out - wait until after your last frost date to be on the safe side.